1. Field of the Invention
This invention relates to high-strength roofing products using novel glass fiber mats, and more particularly, to ashalt shingles and built up roofing products having exceptional tensile strengths.
2. Description of the Prior Art
Thin sheets or mats of glass fibers are finding increasing application in the building materials industry, as for example, as felts in roofing products. These glass fiber mats are replacing base sheets made traditionally of cellulosic and/or asbestos fibers. Glass fiber mats usually are made commercially by a wet-laid process, which is carried out on modified paper-making machine, as described, for example, in the book by O. A. Battista, Synthetic Fibers in Papermaking (Wiley 1964: New York). A number of U.S. patents also provides a rather complete description of the wet-laid process and glass mats produced thereby, including U.S. Pat. Nos. 2,477,555, 2,731,066, 2,906,660, 3,012,929, 3,021,255, 3,050,427, 3,103,461, 3,108,891, 3,228,825, 3,634,054, 3,749,638, 3,760,458, 3,766,003, 3,838,995, 3,853,683, 3,905,067, 4,052,257, 4,112,174, 4,129,674 and 4,135,029.
Unfortunately, however, none of these prior art glass fiber mats possess in combination, the high percentage of uniformly enmeshed individual filament fibers, small diameter voids, and high tensile strength properties which are desirable in application in roofing products, such as built-up-roofing membranes or ply sheets.